Fuel cells have been proposed as a power source for electric vehicles and other applications. In proton exchange membrane (PEM) type fuel cells, hydrogen is supplied as a fuel to an anode of the fuel cell and oxygen is supplied as an oxidant to a cathode of the fuel cell. A plurality of fuel cells is stacked together in fuel cell stacks to form a fuel cell system. The fuel is typically stored in large, hollow, substantially cylindrical pressure vessels disposed on an undercarriage of the vehicle.
The pressure vessels are typically multi-layered and include at least an inner liner and a filament wound outer shell. The pressure vessels may expand or contract when a pressure and a temperature of the fuel within the vessels changes. A restraining means disposed on the pressure vessels must be able to accommodate the expansion and the contraction of the pressure vessels.
To provide the vehicle with a desired travel range and a vehicle appearance consistent with consumer needs, a plurality of the pressure vessels is required. A diameter of the pressure vessels may be limited by a package space adjacent the undercarriage of the vehicle or by a conventional restraining means used to secure the pressure vessels. Accordingly, a length of the pressure vessels may be increased to compensate for the limited diameter or to facilitate the conventional restraining means. As the length of the pressure vessels increases, a ratio of the diameter to the length decreases. The conventional restraining means (typically including a plurality of circumferential bands fastened to a support structure) may be of considerable size and restrict service of the pressure vessels. The pressure vessel having a small diameter to length ratio makes inefficient use of the package space and facilitates the use of conventional restraining means.
The plurality of pressure vessels and associated componentry results in an increased mass of the fuel cell system into which the pressure vessels are incorporated. The pressure vessel may require a regulating valve, a pressure sensor, a pressure relief device, a restraining means, or other devices. As a result, the cost and the mass of the fuel cell system including the plurality of the pressure vessels may become undesirably high.
It would be desirable to develop a mounting system that permits a repeated expansion and contraction of the pressure vessel, restrains the vessel having a large diameter to length ratio, and minimizes a mass of a system into which the pressure vessel is incorporated.